Die structure



, 2v .Sheets-Sheet 1 -HMMI ,NN N

.www H l W/V//%//////////// MN x im@ j@ INVENTOR.

BY xe/ M Ha/m /KL'ZMJ www. mw. .www

A. M. HOLM DIE STRUCTURE 0M. D D,

Oct. 11, 1949.

Filed Sepp. 14, 1945 @www ww A. M. HQLM DIE STRUCTURE 2 Sheets-SheefI 2Filed Sept. 14, 1945 IN V EN TOR @l @u M 1; E m bm, .Y L w Q W PatentedOct. 11, 1949 UNITED STATES PATENT OFFICE (Granted under the act ofMarch 3, 1883, as amended April 30, 1928; 370 O. G. 757) 8 Claims.

The invention described herein may be manufactured and used by or forthe Government for governmental purposes, without the payment to me ofany royalty thereon.

This invention relates to die structure. More particularly the inventionrelates to die structure and apparatus for forming or embossinglongitudinal grooves in tubular members.

In many instances tubular members are used as supporting or guidingstructures and in these instances it is often desirable that the tubularmember be provided with a plurality of circumferentially spaced,longitudinally running grooves to form ribs or rails for a component tobe guided.

Such an instance occurs in the design and manufacture of tubes used inrocket launchers of the type currently employed by the military forces.In a weapon of this type it is preferable to provide a plurality ofparallel launcher tubes in a series or cluster. The weapon is designedso that rockets may be launched from this cluster of tubes in a definitepattern. AAlthough the rocket launcher is essentially a simple weapon,inasmuch as it requires no expensive rifling of the barrel, recoilmechanism, etc., several minor problems have occurred in the manufactureand use thereof. The problem with which the present invention isparticularly concerned is that involving the provision of guide rails onthe inner cylindrical surfaces of the launcher tubes so that the rocketsmay be accurately launched therefrom. It has heretofore been thepractice to provide these rails by rather expensive and complicatedmachining operations. According to the present invention the rails areeasily, quickly and accurately formed on the tube from wall sections ofthe tube itself without any waste of material.

It is accordingly a principal object of the present invention to provideimproved die structure and apparatus for the forming of longitudinalgrooves or ribs in a tubular member and particularly to apply theapparatus to the fabrication of tubes for rocket launchers.

It is an important object of the invention to provide improved diestructure comprising upper member carrying a die, a lower support memberdies and an intermediate mandrel, all designed to conform to the shapeof the tube to be treated; another object is to mount the mandrel for4floating movement between the upper and lower support members.

The invention has for another object the provision of means in themandrel for easily and accurately locating or piloting the tube in which2 the longitudinal grooves are to be formed or embossed.

And another object is to provide means carried by one of the supportmembers for locating the tubular member on the mandrel.

The foregoing and other objects and important features of the inventionwill become apparent as the disclosure is more fully made in thefollowing detailed description and accompanying sheets of drawings inwhich:

Fig. 1 is a plan view of a preferred form of die structure;

Fig. 2 is a transverse sectional view taken on the line 2-2 of Fig. 1;

Fig. 3 is a transverse sectional view, on an enlarged scale, taken onthe line 3-3 of Fig. 1;

Fig. 4 is a transverse sectional View taken on the line -ll of Fig. l;

Fig. 5 is a longitudinal sectional View taken substantially along theline 5 5 of Fig. l;

Fig. 6 is an end elevation of the apparatus; and v Fig. 7 is aperspective view of a tube formed on the apparatus.

Although the preferred form of the invention illustrated herein will bedescribed in connection with the formation of longitudinal grooves on atubular member particularly designed for use in rocket launchers, itwill be understood that the several features of the invention aresimilarly applicable in other instances. Accordingly, the presentdisclosure should be taken as illustrative and not limiting.

The die structure illustrated herein is especially adapted for use inany conventional type of press and includes means by which it may besupported on the base or table of such press and means that may beoperated by the movable member of the press. For these purposes the diestructure is provided with a base member I0, including a lower supportmember II, and an upper movable member I2, including an upper supportmember i3. The base I0 is provided with longitudinally spaced Verticalslide rods I4 which pass respectively through openings I^5 formed in theupper member E2. Each slide rod I4 is provided adjacent its upper endwith a bushing I6 so that the upper member I2 may be freely carriedthereon. As best shown in Fig. 6, the lower support member II is rigidlycarried by the base I0 and is provided with a longitudinal arcuate orconcave surface Il' that conforms to the outside diameter of a tubularmember to be formed in the die structure. As shown in the same ligure,the upper support member I3 is rigidly carried by the member I2 and isprovided with a longitudinal concave or arcuate surface I3 diametricallyopposed and complementary to the surface I'I of the lower support memberII.

The base I carries adjacent one end thereof a support I5, which, as bestshown in Fig. 4, is generally in the form of an inverted U havingopposite vertical members 26 and an upper transverse member 2I. Thesupport I5 further includes a lower transverse member 22. bers 26, 2|and 22 are rigidly secured together, preferably by welding, and themember 22 is rigidly secured to the base I by a plurality of recessedcap screws 23. The members 25 are provided with transversely alignedbores 26 in which 1 is mounted a transverse pivot pin 25. serves tosupport a longitudinally mandrel 26.

The mandrel is cylindrical in cross section substantially throughout itslength and conforms generally to the inside diameter of a tubular memberto be treated, its outer cylindrical surface being concentric with theconcave or arcuate surfaces il and I8 in the lower and upper supportmembers II and I3 respectively. That portion of the mandrel 26 thatprojects away from the support structure I I-I3 is formed withdiametrically opposed iiat sides 21. This portion of the mandrel isseparated from the cylindrical portion by a circumferential flange orpartial collar 28. The portion of the mandrel including the flat sides2l is provided with a transverse, vertically elongated opening 29through which the pin 25 passes. As shown in Figs. 4 and 5, the'upperand lower sur- This pin extending faces of the mandrel are verticallyspaced rebetween the upper and lower support members II and I3.

The base I Il is provided at a portion thereof spaced from thesupporting means I il with a second support indicated generally by thenumeral 36. As shown in Figs. 1 and 2 this support includes a lowertransverse member 3i, rigidly secured to the base I6 by a plurality ofrecessed cap screws 32, and a second member 33 in the form of aninverted U that embraces the free end of the mandrel 26. The crossportion of the U-shaped member 33 is spaced a substantial distancevertically above the end of the mandrel 26. This space is occupied bymeans resiliently mounting the mandrel 26 on the support I9 so that thefloating movement `of the mandrel is resiliently opposed. The resilientmeans serves to maintain the mandrel 26 normally in the position shownin Fig. 5; that is, with the upper and Ilower surfaces thereofsubstantially equally spaced from and parallel to the upper and lowersupport members I3 and II respectively. The resilient mounting comprisesa first member 34 having an under arcuate surface tting an upper arcuateportion of the left-hand end of the mandrel 26. A pin 35 pilots themember 3d on the mandrel 26. A second member 36, generally in the formof an inverted U, carries a block of resilient material such as rubberor the like, indicated generally at 3l, and is carried by the firstmember 34 within the legs of the U-shaped member on the support 36. Theresilient block 3l is thus confined between the inner surfaces of themember 36 and the upper surface of the member 36.

As best shown in Fig. 6, that portion of the The memrespective groove38.

mandrel 26 that lies between the upper and lower support members i3 andI I is provided with three circumferentially spaced, longitudinallyrunning grooves 38. The upper support member I3 is provided with alongitudinally running grooveforming die element preferably in the formof a hardened steel insert 39. The insert 39 is rigidly carried by theupper support member I3 by means of a plurality of removable cap screwsli. The edge of the insert 39 is rounded and is complementary to theupper groove t8 in the mandrel 26.

The upper support member I3 carries thereon a plurality of means forassisting in locating a tubular member to be received by the mandrel 26.In the present instance there are four such means and each comprises alocating member Il! resi-liently mounted on and depending from the uppersupport member I3. Each member 4I is provided with a pair oflongitudinally spaced transverse bores 42. Adjustable screws 63 arepassed loosely through the bores I2 and into threaded bores formed inthe upper support member I3. Each adjustable screw 43 carries acompression spring 44 interposed between the head of the screw and theproximate side of the loeating member 4I. The action of the springs lllis such as to resiliently maintain the positions of the locating members4I normally as shown in Fig. 6. When a tubular member is mounted on themandrel 26, the locating members ll may yield laterally outwardly andthe members will rest firmly against the side of such tubular member andwill assist in locating the same on the mandrel.

The mandrel 26 includes radially extendible and retractable means forlocating the tubular member to be treated on the mandrel. This means isbest shown in Fig. 3 and comprises a pair of radially movable plungersi5 mounted in bores formed respectively on radii of the mandrel thatintersects the opposite side grooves 38 in the mandrel. The outer end ofeach bore is concave as at 46 and is coincident with its A vertical borelll' formed in the mandrel 26 carries slidably therein a centeringplunger 48. A compression spring 49 urges the plunger 48 downwardly inthe bore lll and against the angularly disposed plungers 135. Each ofthe plungers 45 and 69 has a conical inner end so that functioning ofthe locating means is accomplished easily and accurate-ly. Each olf; theplungers 45 is cut out at its upper surface as at 50 and engages a pin5I firmly in a bore 52 drilled in the mandrel 26 at an angle to theplunger 45. The pins 5I, by engagement with the cutouts 50, limitextension and retraction of the locating plungers 45.

An example of a tube fabricated in the die structure just described isshown in Fig. '7. The tube is indicated generally by the numeral 53 andis provided with three longitudinally running circumferentially spacedgrooves 54. The formation of the grooves 543 is such that the interiorof the tube 53 is formed with a corresponding number of longitudinallyrunning, inwardly directed ribs or rails 55 (only one of which is shownin Fig. 7). The function of the apparatus is such that the ribs 55serve, in the case of fabrication of launcher tubes, as rails forguiding the rockets to be fired. In the fabrication of the preferredproduct illustrated, the grooves 54 terminate short of one end of thetube 53. For this purpose the upper portion of the mandrel 26 isprovided with a shoulder 56, and a complementary shoulder .51 is formedon the under surface of the groove-forming insert 39.

Operation The positions of the parts before the tube 53 is mounted onthe mandrel 26 will be as shown in Fig. 5. The support 30, including theresilient mounting 31, will maintain the mandrel in position with theupper and lower portions of its cylindrical surface substantiallyequally spaced from the arcuate surfaces of the upper and lower supportmembers I3 and Il (Fig. 6). The curved edge on the groove-forming insert39 in the upper support member I3 will be correspondingly spaced fromthe upper groove 38 in the mandrel 26. The spacing between the elementsjust described is substantially equal to the thickness of the wallsection of the tube i53. The tube 53 is then slid endwise on the mandrel26 and one end thereof abuts against the half-collar 28| on the mandrel.Pressure of the spring 49 in the vertical bore 47 of the mandrel urgesthe locating plungers 45 radially outwardly against the smooth innercylindrical surface of the tube. The springs M urge the locating members4I firmly against the smooth outer cylindrical surface of the tube. Theupper member I2 is subjected to pressure of a conventional press or thelike and the upper support I3 moves downwardly toward the lower supportII. The tube 53 is firmly held on the mandrel 26 between the upper andlower support members and the groove-forming insert 3S embosses or formsinwardly a longitudinal section of the wall of the tube 53, thus forminga longi tudinal groove 54 in the tube. The inner portion of the wallsection thus embossed conforms to the upper groove 38 of the mandrel 26,thus conforming a longitudinal internal rib f55 on the tube.

After one groove 54 has been formed in the tube 53, pressure on theupper support member is released and the upper member I2 is movedupwardly. The resilient mounting of the mandrel 26 has, during theapplication of pressure on the upper member I2, permitted the mandrel tofloat so that it seats properly in the upper and lower support membersI3 and II. When pressure is released from the support members theresilient mounting permits the mandrel 26 to return to its normalposition as shown in Fig. 5. Because of the slot and pin connection25-29, floating of the mandrel 26 will be accomplished in such mannerthat the mandrel is at all times parallel to the arcuate surfaces I'Iand I8 of the lower and upper support members I I and I3 respectively.The tube 53 is then removed endwise from the mandrel and is rotated 120"(since there are three grooves 54 to .be formed). The rib 55 just formedwill now engage one of the side grooves 38 in the mandrel as the tube`53 is remounted on the mandrel. As the tube is seated against thecollar 28 on the mandrel, the interior rib 55 on the tube will engagethe proximate locating plunger 45. Spring pressure behind the centeringplunger d'8 will cause the locating plunger 45 to contact the rib 55rmly, which, in conjunction with the action of the locating members 4 I,serves to locate the tube 53 accurately on the mandrel 26 preparatory tothe forming of a second groove 54. The forming of this second groove isaccomplished in the manner previously outlined.

After the second groove is formed, the tube 53 is removed from themandrel and rotated another 120 and remounted on the mandrel. The twointerior ribs now formed will be engaged by the locating plungers 45 andthe tube will be properly located on the mandrel. The formation ofthethird groove 54 will occur as previously described.

It will be seen from the foregoing description that a simple andefficient apparatus has been provided for the forming of longitudinalexternal grooves in a tubular member. The design of the structure issuch that the external grooves result in internal ribs that requirelittle, if any, finishing and are suitably adapted for at least theparticular purpose intended; that is, as rails in tubes used in rocketlaunchers. As previously stated, it will be appreciated that the severalfeatures of the invention will iind application in other instances. Itwill also be appreciated that the present disclosure pertains to only apreferred embodiment of the invention and that numerous modificationsand alterations may be made therein without departing from the spiritand scope of the invention as defined in the appended claims.

What is claimed is:

1. Die structure for forming longitudinal grooves in a tubular member,comprising a generally flat horizontal base, a support at one end ofsaid base, a longitudinally extending cylindrical mandrel for receivinga tubular member thereon, there being a plurality of circumferentiallyspaced longitudinal grooves in the cylindrical surface of said mandrel,means including a transverse pivot and a vertical slot connectionmounting said mandrel at one end on said support, means including aresilient element connected between said base and said mandrel andmounting said mandrel in position to extend normally above and parallelto said base, a lower support member carried by said base below saidmandrel and having an upper concave surface generally concentric withsaid mandrel, an upper support member disposed above said mandrel andhaving an under concave surface generally concentric with said mandrel,means mounting said upper support member on said base for verticalmovement, and a groove-forming die element rigidly carried by said uppersupport member longitudinally thereof and in alignment with one of thegrooves in said mandrel.

2. Die structure for forming longitudinal grooves in a tubular member,comprising a generally iiat horizontal base, a longitudinally extendingcylindrical mandrel for receiving a tubular member thereon, there beinga plurality of circumferentially spaced longitudinal grooves in thecylindrical surface of said mandrel, means including a resilient elementconnected between said base and said mandrel and mounting said mandrelin'position to extend normally above and parallel to said base, a lowersupport member carried by said base below said mandrel and having anupper concave surface generally concentric with said mandrel, an uppersupport member disposed above said mandrel and having an under concavesurface generally concentric with said mandrel, means mounting saidupper die member on said base for vertical movement, and agroove-forming die element rigidly carried by said upper support memberlongitudinally thereof and in alignment with one of the grooves in saidmandrel.

3. Die structure for forming longitudinal grooves in a tubular member,comprising a generally flat horizontal base, a longitudinally eX-tending cylindrical mandrel for receiving a tubular member thereon,there being a plurality of circumferentially spaced longitudinal groovesin the cylindrical surface of said mandrel, means including a resilientelement connected between said base and said mandrel and mounting saidmandrel in position to extend normally above and parallel to said base,a lower support member carried by said base below and spaced from saidmandrel a distance substantially equal to the thickness of the wallsection of the tubular member to be carried on said mandrel, an uppersupport member disposed above and spaced from said mandrel a distancesubstantially equal to the thickness of the Wall section of the tubularmember to be carried on said mandrel, means mounting said upper diemember on said base for vertical movement, and a groove-forming dieelement rigidly carried by said upper support member longitudinallythereof and in alignment with one of the grooves in said mandrel.

4. Die structure for forming longitudinal grooves in a tubular member,comprising a generally ilat horizontal base, a longitudinally extendingcylindrical mandrel for receiving a tubular member thereon, there beinga plurality of circumferentially spaced longitudinal grooves in thecylindrical surface of said mandrel, means including a resilient elementconnected between said base and said mandrel and mounting said mandrelin position to extend normally above and parallel to said. base, a lowersupport member carried by said base below and spaced from said mandrel adistance substantially equal to the thickness of the wall section of thetubular member to be carried on said mandrel, an upper support memberdisposed above and spaced from said mandrel a distance substantiallyequal to the thickness of the wall section of the tubular member to becarried on said mandrel, means mounting said upper supportmember on saidbase for vertical movement, a groove-forming die element rigidly carriedby said upper support member longitudinally thereof and in alignmentwith one of the grooves in said mandrel, and means including a pluralityof radially extendible and retractable elements carried by said mandrelfor locating and centering the tubular member on said mandrel.

5. Die structure for forming longitudinal grooves in a tubular member,comprising a generally flat horizontal base, a longitudinally eX-tending cylindrical mandrel for receiving a tubular member thereon,there being a plurality of circumferentially spaced longitudinal groovesin the cylindrical surface of said mandrel, means including a resilientelement connected between said base and said mandrel and mounting saidmandrel in position to extend normally above and paralle] to said base,a lower support member carried by said base below and spaced from saidmandrel a distance substantially equal to the thickness of the wallsection of the tubular member to be carried on said mandrel, an uppersupport member disposed above and spaced from said mandrel a distancesubstantially equal to the thickness of the wall section of the tubularmember to be car.. ried on said mandrel, means mounting said uppersupport member on said base for vertical movement, a groove-forming dieelement rigidly carried lbv said upper support member longitudinallythereof and in alignment with one of the grooves in said mandrel, meansincluding a plurality of radially extendible and retractable elementscarriedby` said mandrel for locating and centering the tubular member onsaid mandrel, and means carried by one of said support members includingtransversely shiftable resiliently mounted guide elements for assistingin the locating of the tubular member on said mandrel.

5. Die structure comprising a base, a mandrel paralleling said base,means forming a first support on said base, means mounting said mandrelon said first support for floating movement toward and away from saidbase including a rst element on said supporting means and a secondelement on said mandrel, one of said elements comprising a verticallyelongated slot formed in the direction of movement of said mandrel andthe other of said elements including a pin passed through said slotbetween said mandrel and said supporting means, a second support on saidbase adjacent the end of said mandrel and spaced from said firstsupport, resilient means on said second support con.. necting saidmandrel and said base and normally positioning said mandrel in spacedrelation to said base, a die movably carried by said base forcooperation said mandrel, and a concave support member carried by saidbase to support said mandrel against the action of said movable die.

7. Die structure comprising a base, a mandrel paralleling said base,means forming a rst support on said base, means mounting said mandrel onsaid rst support for iioating movement toward and away from said base, asecond support on said base adjacent the end of said mandrel carryingresilient means opposing said oating movement, said means connectingsaid mandrel and base and normally positioning said mandrel in spacedrelation to said base, a die movably carried by said base forcooperation with said mandrel, and a support member carried by said baseto support said mandrel against the action oi said movable die.

8. Die structure comprising a first work support member, agroove-forming die element rigidly carried by said member, a secondsupport member spaced from said rst support member and complementarythereto, a base, means mounting said support members on said base formovement toward and away from each other, a mandrel interposed betweensaid support members and adapted to receive a workpiece to be formed bysaid die element, and means mounting said mandrel on said base foroating movement within limits in the directions of movement of saidsupport members toward and away from each other, said means including apin and slot connection and a resilient element between said mandrel andsaid base.

AXEL M. HOLM.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 340,330 Leadley Apr. 20, 1886535,735 Smiley Mar. 12, 1895 637,875 Kronquest Nov. 28, 1899 890,525Numan June 9, 1908 1,714,108 Schlafly May 21, 1929 1,950,726 GraybillMar. 13, 1934 2,339,032 Schlenzig Jan. 11, 1944 2,389,974 Greig Nov. 27,1945 FOREIGN PATENTS Number Country Date 464,931 Germany Sept. 1, 1928

